Massive New Saturn Ring Challenges Established Ideas about the Solar System

Image credit: NASA/JPL-Caltech) [public domain]

When talking about planetary rings, Saturn is most likely the planet that comes to mind. However, you may have to update your imagination of this beautiful ringed planet. More recent discoveries of NASA say that the outermost Saturn ring spans an area that is thousands of times larger than the other rings of the planet depicted on books and scientific references. Yes, Saturn has another ring that you likely exclude when you imagine the planet.

Phoebe – A Ring with Unusual Features

Space scientists at the University of Maryland found that Saturn’s outermost ring, called Phoebe, is actually larger than earlier estimated. Phoebe, by the way, was discovered only in 2009 through Spitzer Space Telescope of NASA. It was named on account of the influence of Saturn’s eponymous satellite. The ring is described as tenuous or having a thin consistency. It is composed of widely dispersed particles mostly made of dust and ice.

Phoebe is also believed to be the missing link that may help solve the puzzle of the unusual appearance of one of Saturn’s moons, the Iapetus. With one part of its sun-illuminated side appearing bright and the other part looking completely dark, the Iapetus looks like the yin-yang symbol. The discovery of Saturn’s Phoebe ring has led scientists to hypothesize that the dark part of Iapetus is caused by the dark and dusty materials of the Phoebe ring. Scientists who have been observing Phoebe and Iapetus say that some of the dusty dark materials in Phoebe are moving towards Iapetus, such that Iapetus looks like a light-colored object being swarmed by bugs.

Phoebe was discovered not through telescopes that view visible light. Instead, scientists used a longer-wavelength infrared camera referred to as a multiband imaging photometer. The scientists found a belt of dust and had a hunch that there’s something out there they have yet to discover. They focused on the glow of the ring’s cool dust, which had a temperature of only about 80 Kelvin, and finally saw what is now known as the enigmatic and immense Phoebe ring.

The Biggest Ring Ever

Upon its discovery, Phoebe was already known as the biggest ring ever found by astronomers. It was estimated that its distance from Saturn was around 6 million kilometers while its outer edge was estimated to be around 12 million kilometers from Saturn. Now, through more advanced technology, NASA’s Wide Field Infrared Explorer (WISE) telescope in particular, this massive ring’s size has been revised upwards. Phoebe’s edge is now measured to be around 16 million kilometers away from Saturn. This is significantly bigger than earlier estimated. This makes it 20 times bigger than the next biggest ring known to man. It is now up to 270 times as big as Saturn (radius-wise). The numbers may even be raised again in the future as the technology to detect heat signatures in extremely distant objects advances. For now, the small and dark nature of the materials in the Phoebe ring make it difficult to study it.

Dust from Another Moon

The particles in the Phoebe ring could be millions to billions of years in age. They are believed to have originated from one of Saturn’s moons, Phoebe (yes they bear the same name). The particles in Phoebe are also rather unusual. In addition to being so sparsely dispersed (with only about a few dozen particles for every cubic kilometer of space), their sizes are mostly micron-sized or smaller than the diameter of a strand of hair. There are rocks in the ring that are about the size of soccer balls but they are estimated to comprise only about 10% of the materials in the ring.

Moon-like and Unorthodox

University of Maryland planetary scientist Douglas Hamilton, in an interview with Space.com, said that the Phoebe ring’s existence is fascinating considering how far it is from the planet it is circling. The long-established idea is that moons are the ones that are formed so far away from a planet. Rings are expected to be much closer to a planet, which is not the case for Phoebe. Also, Phoebe is believed to be moving at a direction opposite to how Saturn’s other ring are moving. Even more intriguing is the observation that Phoebe does not move in relation to the tilting of Saturn. While other Saturn rings change their position relative to the tilting of Saturn, Phoebe remains in its own tilted position.

It is suspected that Jupiter, given its size, may also have a ring similar to Phoebe. According to Hamilton, whenever a planet has a distant moon, it is likely that it also has a distant ring. Space is indeed remarkably vast and full of mysteries that established information about it are bound to change as new technologies to explore it are developed.